Photophysical and electron attachment properties of ArF-excimer-laser irradiated H-2

Detailed electron attachment and spectroscopic measurements are reported on ArF-excimer-laser irradiated H-2. These studies indicate that previously reported efficient H- formation in ArF-laser irradiated H-2 is due to electron attachment to high-lying Rydberg (HR) states indirectly populated by the laser irradiation. Electron attachment studies indicate a lifetime of greater than or equal to 40 ns for the electron attaching state(s): The spectroscopic studies show that vacuum ultraviolet emission due to the B (1) Sigma(u)(+) --> X (1) Sigma(g)(+) transitions continues for up to similar to 100 ns after the termination of the laser pulse and thus that the B state is populated by cascades from higher-lying states with longer lifetimes. The temporal profile of Lyman-alpha emission due to the H(n = 2) to H(n = 1) transitions is consistent with the production of H(n = 2) states by electron attachment to HR states.